Refrigerant Distributor Pipe Sizing for Balanced Heat Exchanger Flow

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Solution Overview

Problem

The existing refrigerant distributor configurations in refrigeration cycle apparatuses are complex and difficult to fabricate, requiring high dimensional accuracy and separate fabrication of throttling members, which complicates the manufacturing process and can lead to inefficiencies in heat exchange due to imbalances in refrigerant flow.

Innovation Solution

A refrigerant distributor with a simple configuration, where the inlet pipe has a smaller inside diameter than the distribution pipes connected to heat transfer tubes, ensuring a balanced refrigerant flow by varying the inside diameters of the distribution pipes based on their connection levels, preventing imbalances and reducing heat exchange efficiency issues.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a separate throttling member is attached to the dividing pipe to achieve appropriate pass balance, then refrigerant flow balance is improved, but device complexity and manufacturing difficulty increase

Engineering Contradiction:
Improverefrigerant flow balanceVSAvoiddividing pipe configuration
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The invention merges the throttling function and dividing pipe function into a single integrated component. The dividing pipe is designed with varying inside diameters at different locations to provide throttling effects, eliminating the need for separate throttling members and simplifying the overall structure while maintaining refrigerant flow balance.

Inventive Principle:
Principle #5Merging (Combining)

Solution Approach 2:

The dividing pipe is designed to perform multiple functions simultaneously: it distributes refrigerant to multiple branches and provides throttling control through its varying inside diameter. This multi-functional design reduces the number of components needed while achieving both flow distribution and flow balance.

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Reliability

If high dimensional accuracy is required for the inside diameter of open ends and outside diameter of throttling member, then pass balance is improved, but manufacturing precision requirements and fabrication difficulty increase

Engineering Contradiction:
Improvepass balanceVSAvoiddimensional accuracy
Core Design Contradiction:
ReliabilityVSManufacturing precision

Solution Approach 1:

The dividing pipe is designed with different inside diameters at different locations along its length. The inside diameter varies locally to provide appropriate throttling effects for each branch, allowing for pass balance adjustment without requiring high dimensional accuracy at specific attachment points of separate components.

Inventive Principle:
Principle #3Local quality

3Reliability

If separate fabrication and attachment of throttling member to dividing pipe is performed, then pass balance control is improved, but ease of manufacture deteriorates

Engineering Contradiction:
Improvepass balance controlVSAvoidfabrication process
Core Design Contradiction:
ReliabilityVSEase of manufacture

Solution Approach 1:

The throttling function and dividing pipe function are combined into a single monolithic component. The dividing pipe is fabricated as one piece with varying inside diameters, eliminating the separate fabrication and attachment steps required for separate throttling members, thereby simplifying the manufacturing process.

Inventive Principle:
Principle #5Merging (Combining)

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

This configuration achieves a good pass balance of refrigerant in the heat exchanger, preventing a reduction in heat exchange efficiency and simplifies the fabrication process by using a straightforward design that maintains high heat exchange efficiency in refrigeration cycle apparatuses.

Implementation Method 1

The inlet pipe of the refrigerant distributor having a relatively low average value of levels of the plurality of distribution pipes connected to the plurality of heat transfer tubes has a smaller inside diameter than the inlet pipe of the refrigerant distributor having a relatively high average value of levels of the plurality of distribution pipes connected to the plurality of heat transfer tubes

Methodology Applied
Scientific EffectFluid flow restriction through diameter variation: Pressure Gradient

Data Source

PatentEP3614075B1Heat exchange unit and refrigeration cycle apparatus
Publication Date: 2022.07.20 MITSUBISHI ELECTRIC CORP
  • EP3614075B1 patent drawingFigure 1
  • EP3614075B1 patent drawingFigure 2~3
  • EP3614075B1 patent drawingFigure 4~5

AI summary

A heat exchange unit includes a heat exchanger including a plurality of heat transfer tubes and a plurality of refrigerant distributors. Each of the plurality of refrigerant distributors includes an inlet pipe through which refrigerant flows into the refrigerant distributor and a plurality of distribution pipes through which the refrigerant flows out of the refrigerant distributor. Each of the plurality of distribution pipes is connected to a corresponding one of the plurality of heat transfer tubes. The inlet pipe of the refrigerant distributor having a relatively low average value of levels of the plurality of distribution pipes connected to the plurality of heat transfer tubes has a smaller inside diameter than the inlet pipe of the refrigerant distributor having a relatively high average value of levels of the plurality of distribution pipes connected to the plurality of heat transfer tubes. In each of the plurality of refrigerant distributors, the distribution pipe that is included in the plurality of distribution pipes and that is connected at a relatively low level to the heat transfer tube has a smaller inside diameter than the distribution pipe that is included in the plurality of distribution pipes and that is connected at a relatively high level to the heat transfer tube.